Thermal barrier coating systems are mostly used on nickel-base or cobalt-base systems as base material, in which case, to improve the mechanical properties, the proportion of the γ′ phase is increased by additions of aluminum and titanium. However, since titanium has a very high diffusion coefficient at the temperatures of use, titanium diffuses from the base material into a bonding layer of the MCrAlX type in the layer system, where it is incorporated in the thermally grown aluminum oxide layer (TGO), so that titanium spinels, which have very unfavorable effects on the bonding of a ceramic layer above, are formed on the bonding layer.
The MCrAlX bonding layer is often coated with platinum in order to prevent this diffusion, but the costs of this are very high.
EP 0 489 659 B1 discloses a process for treating metals in which metallic halides are applied as a layer.
Therefore, it is an object of the invention to overcome the abovementioned problem.